Method of forming eyes in wire



...|IIIIIIL.

c. L. HOFF Er AL METHOD oF FORMING EYES 1N WIRE* Filed` lay 28, 1925 I May 21, 1929. f

Patented May k21, 1929.

UNITED STATES 1,713,964 PATENT oEFlcE.

CARLTON L. HOFF AND GIRARDUS NAUGLE, YORK, PENNSYLVANIA, ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, T HOFF yME'L-kl'i PRODUCTS C0., OF YORK,

PENNSYLVANIA, A CORPORATION OF DELAWARE.

METHOD 0F FORMING IN WIRE.

Application filed May 28, 1925.I Serial No. 33,487.

The invention relates to a method for forming curvilinear bends, such as eyes, at the end of a wire, bar or similar metallic form.

Eyes, hooks, loops and similar configurationsnow form ed in wires,bars and the like develop structural weakness at'localized points apparently due `to the manner in which the wire or bar is bent. In forming such eyes, hooks, loops and similar configurations in the manufacture of chains,andinlike metal Work,

it is a usual practicev to bend the Wire about a post or mandrel, commonly called a king pin.

In these operatonsthe metal which is usually drawn wire and, therefore, contains internal f stresses, is stretched about the king pin and this develops additional internal stresses and apparently acts to cause a crystallizing of the part of the bend which-is on the internal side. Vhen the metal stock is operated upon in a wire bending machine, the turning of the stock about the mandrel is done in a series of succeeding steps, at each step-the pressure being applied at a different point with the result that the pressure is applied unevenly. The resulting tendency of suoli movement about the mandrel. is toweaken the metal at the several bends and this weakening factor increases rapidly with the sharpness of the angle termed or with the reducing of the internal diameter where the metal is bent into circular eyes.

When the known form of eyes are Subj ected to breaking tests, the break invariably takes place at the apex of the sharpest angle.

The primary object of the invention is to provide an improved methodof forming a bent Wire or bar in which the physical characteristics of the part at the ben-d are not materially different from the unbent part and thus to provide a bend or eye, thediiferent portions of which will have substantially uni form strength.

In forming eyes and like ben ds mechanically the method has been most conveniently practiced on a form of machine, known as a. four-slide wire bending machine, and which includes four sets of slides or dies, control cams for moving the dies, certain clamping parts and one or more king pins about which the wire is bent by the action of the dies.

Such machines function with 'satisfaction provided the eye or other configuration is of relatively large internal diameter compared with the size of the Wires, bars, or other Stock material used. However, whenever anattempt 1s made to form a small size eye Witha relatively large diametered wire, enormous y strains are imposed on the kingpin. As the king pin-must necessarily be made, of small diameter to permit the formation of a small size eye, it is mechanically impossible to prevent distortion and shearinef off of the small, and therefore relatively frail, king pins. Numerous attempts have been made to reinforce the Y king pins but .their small size renders this impossible and as a result small size eyes have not heretofore been formed of large gage wire on these machines.

Accordingly, anotherobject of the invention is to provide for the formation of an eye or bend at the end of a wire or other stock without necessity of using a king pin or other former at the inner sideof the bend and t0 effect this formation simply, economically and independent of the relative size of the bend and of the stock used. i. Y

Broadly, we attain these objects by two bending operations impressed in sequence on the end of the wire or other material to be bent. The first step consists in slightly bending the wire or stock so that it forms an obtuse angle with the unbent portion. The second step consistsin causing a tool having a convexed forming face to engage the pre-bent end and by applying the necessary pressure towards and in line with the unbent portion to continue the formation of the eye beyond the preliminary bend. The movement of the tool is continued until the desired de ree of bend is attained, or until the free en is bent entirely back upon itself and contacts with the unbent portion to form a completely closed eye as featured in this'disclosure.

Another object of the invention is to -provide for the formation of hooks, eyes and the like from wire, sheet metal, bars and other standard forms Without necessity of heating the stock forms; to form the complete eyes or parts thereof in accurate, circular form, to distributethe strains symmetrical relativeto a longitudinalv central core line and at the same time minimize, if not entirely eliminate tendency of the met-al to crystallize, distort, compress or otherwise weaken at localized points of the bend as is usual with similar bent configurations when bent about a mandrel or king pin.

Various other objects and advantages of lil the invention will be in part obvious from a consideration of the method features of the invent-ion herein mentioned and from an inspection of the accompanying drawings; and in part will be more fully set forth in the following particular description of one method of practicing the invention and in the inspection of one form of tool units in a fourslide wire bendingl machine herein illustrated to form an embodiment of the mechanical features of my invention; and the invention also consists in certain new and novel modilications of the preferred method and of other features of construction and combination of parts hereinafter set forth and claimed.

` In the accompanying drawing there is shown in plan view certain of the tools forming part of a conventional form of four-slide wire bending machine, with sii: of the wire shaping slides or dies in four succeeding positions to form a chain link with an eye at each end and illustrating one article designed to be formed by the method featured in this disclosure and in the final figure is a showing of another form of bent article capable of being formed by the method herein featured and both forms having the characteristics featuredv in this disclosure.

Figure 1 shows the position of certain of the parts following the usual operation of the machine in cutting off a length of wire, from the stock fed thereto, and with the laterally moving slides or dies about to engage the straight length of wire to give the ends of the cut-olf stock their preliminary bends;

Figure 2 shows the slides or dies in position at the ends of the preliminary bending operation and with the ends of the wire slightly bent; l

Figure 3 shows the succeeding step with the laterally movable slides withdrawn into their inoperative positions, and with the side slides or longitudinal slides or dies in this view shown in horizontal section engaging the prebent ends and starting on their final bending operation; and l y Figure 'l shows these side slides in their final position with the eyes' completely formed at opposite ends of the wire.

In the form of the invention herein selected for specific discussion in describing the method aspect of the invention both ends of a wire are bent to form complete eyes and this form of resulting article has been selected because the opposing action of the longitudinally moving dies during the final ceiling step act in directions towards each other and in this way there is eliminated any necessity of providing additional holding means for securing the unbent portion of the wire.` It is obviously within the scope of the disclosure` however, to form a hook or eye at one end of the wire following the methods herein suggested and in which case, of course, necessary holding means, stops and clamps will have to be provided to prevent accidental movement of the wire during the final bending movement and it is also obvious that the unbent portion be reduced in length even to the point of elimination.

In the following description and in the claims, parts will be identilied by specific names'for convenience of expression but they are intended to be as generic in their application to similar parts as the art will permit.

Referring particularly to Figure 1 of the drawings itI will be noted that a length of wire lV is clamped in position in the machine and is held in operative positionbetween the front edge of a spring pressed plunger and thel rear face of a front hacker 11. The plunger is carried by a. swinging support 12 which is the usual king post plate, and it is understood that both the front hacker 11 and the king post plate 12 are mounted to have a timed movement transversely of the lengthv of the wire held thereby. At each end of the wire there is a set of similar bending slides or dies which are each designed to operate in unison with the corresponding element at the opposite end of the length of wire, and, except for necessary reversal in position and direction of travel,- the detailed description of the mechanism at one side of t-he machine will be sufficient for the description Aof the similar mechanism at the other side.

Referring particularly to Figure 1 there is disclosed on each side a rear slide 13 .and a front slide 14 disposed on opposite sides of the adjacent end of the wire W. In the instant case it is proposed to form both eyes on the same side of the body portion of the wire, and accordingly one of the eyes is formed clockwise and the other' anti-clockwise as shown in Figure 4. In the operation of the mechanism the dies are moved towards each other to effect an initial or preliminary bend on the end of the wire W. In the showing in Figure 2 it will be noted that the initial bends Z) are directed transversely of the length of the wire and upwardly on the sheet. In order to effect this initial bend the active face 15 of the slide 13 is Vof less width than the opposing face 16 of the frontslide 14;. The outer edge of the face 15 is rounded as shown at 17 and the out-lapping projecting part 18 of the face 1G extends beyond the inner, substantially flat portion 19 of the said face so as to form a curved surface to the die and otherwise the parts are so proportioned and designed to give the end of the wire the slight bend, say shown in Figure 2 and thus to cause the extreme ends to form an obtuse angle with the unbent central portion o of the wire.

The projecting part 18 of the left die 16 is employed as a cutting tool to cut off the length of wire WV from the ystoclewhich is fed to the machine from left to right as indicated by the arrow in Figure 1. They corresponding right die 14 is providedy with an extension 21 which provides a stop for limiting the advance of the stock material into its position to be severed by thecutting tool.

In the sequence of operations of the machine, the transversely movable front and rear slides 13 and 14 retreat as shown in Figure 3, away from the wire bent thereby, so as to permit the movement into position at each bent end of a longitudinally movable side slide or die 22. The side slides are guided to move at right'angles to the direction of movement of the laterally movable slides and to move parallel to the length of the unbent portion of the wire, During this bendingl operation, the side slides move simultaneously towards each other, with the wire therebetween, as indicated by the arrows in Figure 3. The inner, work engaging face 23 of each of the side slides,` is recessed intermediate its top'and bottom surfaces to form a deep recess 24 for receiving the preliminary bent ends of the wire facing the same.

The recess is defined by a J-shaped wall curved to the round configuration of the wire IV, and the forward portion of which wall is straight as shown at 25. This straight portion extends parallel to the unbent portion c of the wire and extends parallel to its direction of movement so as to engage the unbent portion of the wire during the entire period of its-bending movement. The straight portion 25 of the wall merges into a smalldiametered, semi-circular rear wall 26 facing the end b of the wire.

The recess is outlined at top and bottom by flat, smooth, parallel walls 27 which act to confine the movement of the curling end of the wire in the plane of the initial bend and also of course in the plane of the completely formed eyes.-

It is a feature of this disclosure that the portion of the slide outlining the straight wall 25 constitutes ,a rugged projection 28 which advances beyond the portion of the wire being bent and acts to defeat any tendency of the unbent portion c to buckle during the final bending movement of the side slides. If this extension was omitted and the recess formed solely of the semi-circular portion at 2G the wire would bend or buckle between the former and the point at which it is clasped by thc central holding means.

In operation it will be understood that the machine is set so that the different slides will have a proper vtimed sequence of operation to clamp the wire between the aws provided by the members 1() and 11 and thus the laterally moving dies function to cut ofl'al length of wire or other stock, which cutting is usually done by the edge 29l of the front left slide 14.-. The laterally movable dies 13 and r11i are then continued in their movement towards each other past their position shown in Figure 1 and finally into the position shown-in Figure 2. In this advance the two sets of transversely movable slides engage their respective ends of `thewire to give it nary bend is apparently vnecessary but the degree of bend is immaterial. Where it is desired that the end should be bent hack upon itself with the end face e contacting with the unbent portion and having the endportion project perpendicular to thelength of the unbent portion as indicated by the directional lines p in Figure 4l, then, it is neceswsary Vthat care be exercised in the degree of vbend vof about 300 was rfound to be satisfactory and the end'face c just touches the unbent portion 0. n

The neXt step inthe operation'of the machine draws the transversely movable slides from their engagement with the pre-bent wire and moves the same into an inoperative position shown in Figurev 31.. This clears the space at the ends of the wire and permits the advance of the longitudinally movable slides or dies. During this time and in fact until the desired article is completely formed, the cent-ral, unbent portion c of the wire is held clamped between the backer. I

As the longitudinally movable slides are advanced the partially bent ends I) arev received in the recesses in the advancing ends of the side slides. As each slide advances it contacts with the bent end, engages theo'uter side along a relatively long line and turns the end forcefully but smoothly into the circular forni Ai shown in Figure t. It is obvious, however, that the advance of the longitudinal dies may be intercepted at any point in their advance should it be desired to fol-niay J- shaped hook or an incompletely closed eye.

It is particularly noted that there is no king pin or other former to give character to 'the inner periphery to the bend z'. The. bend is formed. Vsolely by the action of the former engaging the outer[periphery of the initial bend, not in a series of spaced points but along its entire surface. The heavy wire in the instant case is simply pressed inwardly and the configurationofthe J-shaped recess in the'side dies forms the eye.

The parts of the machine are lnecessarily `made rugged and the longitudinally moving dies are particularly made strong and must be powerfully actuated,particularly where large gage wire or other difficultly bendable heavy stock material is used.l 'INhen proper- Athe preliminary short bend particularly `shown in Figure 2. Some degree of prelimiplunger and the front ly pressed the ends of the wire simply curve into the circular eye form as if made of some soft plastic material instead of the tough steel which has been used in practice in making certain rugged articles such as antiskid devices for automotive tractor wheels.

By practicing the method herein disclosed it has been possible in quantity production to manufacture extremely small diametered eyes'on heavy bars or on wire of large gage. It has been even possible to form eyes from wire of circular cross section with the diameter of the eye opening, o, less than the diameter of the cross section of the wire used. Every eye formed with a particular setof dies corresponds in dimensions and in every other detail to the configuration of each other eye formed on such dies. The turned partof the eyes both at their internal and external periphery and except at their extreme ends are parts of two circles, present smooth surfaces, and there is avoided the tool marks which are so objectionable in eye constructions which have been formed about king nns. l A. conventional form of wire bending;` machine can be used to form different sized eyes and to use different sized materials, simply by substituting the proper size and configura` tion of slides and dies to meet the requirements of the stock worked upon, and by means of the usual cam controls the advance ot the several dies may be regulated.

While the `method phase of the invention has been described particularly in connection with its operation on a wire bending machine, it is appreciated that the method can be worked independent of the apparatus suggested and as an illustration cfa dilerent mode of operation it is suggested that the preliminary bend be provided. either by hammering one side of an end ot the wire or by bending the wire as an incident to the operation of the longitudinally movable slides. It has been Jfound, however, from practice that a better product is produced and less strain is imposed upon the machine by forming the preliminary bend as a separate and distinct step from the linal longitudinal bend.

Eyes and similar bends of the type herein described are usually formed from drawn wire and similar structural shapes. As a result of the drawing operation in forming the shapes they contain internal stresses usually extending longitudinally and when bent about a king post the iibre of the metal is even further stretched; the internal stress state is complicated, becomes quite noticeable in localized places, and frequently causes a crystallizing of parts with resulting areas of extreme weakness.

Eyes of other forms of bends obtained by practicing the method herein disclosed are free ot these localized areas of weakness.

The part forming the inner periphery of the eye or bend is of course placed under compression and the outer periphery is under tension but the central core is neutral. The usual longitudinally extending strains disappear as the result off cold iiowing of the metal i'rce of the restraint which would otherwise beimposed thereon if bent about a king pin. Apparently the particles ot the metal are tree to flow internally and thus adjust thel'nselves vwithout restraint to their final position in the finished article. There is produced a bent element of uniform strength. in its different parts, and having greater tensile strength as a whole than similar shaped elements heretotore made troni the saine stock material.

The article producedv in the showing in Fig. 4l is intended to be used as the tread member or tovsupport tread members of an anti-skid vehicle chain similar to those shown in Reissue Patent 16,680, July 19, 1927. In such structures it is usual to form the members of relatively heavy wire stock in order to give long life and wear to the tread member and connect their ends to side chains formed of relatively narrow diametered stock. The present disclosure therefore features the tormation of small diametered eyes o at opposite ends of the bar and which eyes are preferably of a diameter no larger than is necessary to receive the thin wire side links. Forming the eyes without the use a former or mandrel as herein featured permits the curling of the ends of the heavy rod or wire into eyes smaller than has been possible heretofore. As the eye is formed from round stock and without the use of a mandrel or other former which would tend to flatten out the inner periphery of the eye, it follows that the inner periphery is defined by a line, almost circular when the eye is completely closed and this provides a line bearing between the ends of the tread members and the side chain links thus tending to minimize resistance to relative movements between the tread members and side chains. As the eye can be made small enough to snugly receive the small side links any looseness of play or objectionable rattle between the tread members and side chains have been minimized. As the full cross section of material of the wire stock is retained up to the end of the eye an extremely rigid form of eye is provided and any tendency of the side chains to pull open the eye is minimized. v Having thus described our invention, we claim f 1. I n the art of forming eyes and similar sharp, curved bends at an end of a straight metallic form without the use of king pins or other forms for defining the configuration of the inner side of the bend, the method which consists in slightly bending the end laterally to cause said end to project slightly from the unbent portion in the direction in which the final bend is to extend, pressing on said laterally bent end in the direction of the unbent portion with a suitably contoured bending tool and continuing the advance of said tool until the desired configuration of eye or other bend is attained on one Side of the unbent portion While engaging the opposite side to secure the unbent portion against any tendency to buckle during the final bending action.

2. In the art ot forming eyes at the end of a Wire and on one side thereof Without the use of a former for the inner periphery of the eye, the'method which includes the step of applying forcein a direction longitudinally of the length of the unbent portion of the wire to turn the same about an arc of more than one hundred and eighty degrees thereby to cause the end of the wire to curl back upon the adjacent unbent portion While securing said unbent portion from buckling and While the inner periphery of the eye is free of restraint'during its formation.

3. In the art of forming eyes at the end oi a wire with the inner periphery of the eye tree of restraint and disposed entirely on one side of the axis of the unbent portion of the Wire, the method which consists in causing an end of the Wire to coil back about an arc of more than one hundred and eighty degrees and into abutting relation against one side of the adjacent unbent portion and providing a stop for engaging the opposite side of said unbent portion to prevent the same froi buckling. y v

4. In the artl of forming eyes at opposite ends of a length of Wire, the method which consists in bending slightly the ends oft-he Wire in the direction in which the eyes are to extend from the intermediate portion, and

causing a pair forming dies to engage the outer sides of the bent portions and to act thereon simultaneously in opposite directions .and constitute the sole means for curling the ends backwardly and thus form the ends of the Wire into eyes free of engagement with any forming member Within the eye.

5. In the art of forming eyes on the end of a Wire Without the use of a former for the inside of the eye, the method Which includes the step of engaging the outer side of the end ora curved Wire and forcing said end back- Wardly into abutting engagement with the unbent portion of the Wire While permitting the inner periphery oit the eye to be free during the bending operation and While permitting the end of the Wire vforming the eye to move freely during its final movement in completing the eye. i

6. In the art of forming eyes at opposite ends of a straight length of Wire and on one side thereof, the method Which consists in slightly bending opposite ends in the direction in Which the eyes are to be formed and in each case With a single bend, and causing a pair of forming dies With vJ-shaped grooves facing towards each other simultaneously to move into position to receive the adjacentv bent end into its associated groove and act thereon to cause both ends simultaneously to coil back upon themselves to form the eyes.

This specification signed this 20th day of May, 1925.

. CARLTON L. HOFF. This specification signed this 20th day of May, 1925.

GIRARDUS G. NAUGLE. 

